The Pure Data (short Pd) project on SourceForge unifies the extensions (or externals) written for the Pure Data Graphical Computer Music System written by Miller Puckette with contributions from many others.

NOTE: Csound's SourceCode, Issue Tracker, and Wiki have moved to http://www.github.com/csound/csound. File Releases and Mailing Lists remain here on Sourceforge at this time.
Csound is a sound and music synthesis system, providing facilities for composition and performance over a wide range of platforms. It is not restricted to any style of music, having been used for many years in at least classical, pop, techno, ambient

This is one of the most popular Doom source ports. It is available for DOS, Windows, Linux and Mac OS X, and should build on any POSIX platform which supports SDL. It enhances Doom with things like TCP/IP networking, OpenGL renderer, Heretic support and much more.

As a library of classes for generating and manipulating music and sound, jMusic provides a solid framework for computer assisted composition in Java. jMusic has a music data structure based upon note/sound events and methods for modifying and structu

XPaint is a simple paint program for X, suitable for producing simple graphics. It does offer some advanced features such as image processing functions and gradient fill.
XPaint was originally written by David Koblas.

WideStudio is an Integrated Development Environment (IDE) for building window applications in C++, Ruby, Python an Perl for Windows, MacOSX, Linux, FreeBSD, SOLARIS and other unix and BTRON and T-Engine. This is open and free (under MIT/X Consortiun Lice

SETEdit is a friendly text editor. It is a text mode application with windows, buttons, mouse support, etc. The main target of the project are programmers so the editor is mainly oriented to programming.